As the title implies I'm going to drop the bomb as early as now and say Odyn would be the ENDGAME boss for Shadowlands.
I will release a series of discourse as we go along the development of Shadowlands contents from, Alpha, beta, live and various interweaving topics.
Shadowlands deal with the mythos of afterlife in WoW and the enigmatic status of the departed. Is there a life after death? What is on the other side?
"This world is a prison, and I will set us all free." - Sylvanas Windrunner
The dead stays dead not until there is somebody to beckon them to ressurect back to life. There are priests, paladins, druids, shamans and other methods such as soulstones, defiblators and others. Then there are Valkyrs.
Since SL is still currently on Alpha, I wouldn't drop everything all at once but I have some evidence ready, waiting.